Can anyone recommend an decent and affordable air purifier?

I used to have a Sunbeam. It was quiet enough so that I could use it at night, small enough to fit in a corner, and strong enough to clean the air. I don’t use it anymore, but my mom does and she says it still works as f it was purchased yesterday. I’ll try to find out what kind it is and let you know.
Edit: It’s the one pictured on the box here, but I can’t find the specs about it.

Are you going to ask your roommate friends to pay for the refills?

“After all, we are all using it!”
– Ross Gellar

I’ve had a Hunter HEPAtech for two years now, and it is awesome.
Fits on my bedside table, easy to clean, and is also an ionizer.
Plus, having it on all the time is great white noise, and helps me sleep better.
I’m sure most brands will do as well, but I’m happy with this one; if I ever have to replace it, I’ll shop till I find a similar one.

I have a Holmes HAP2400B-U Air Purifier. It is a HEPA type with an ionizer function. I paid about $32 for it. Works great in a room that is 10×18. Replacement filters run about $12. Filters are supposed to last around three months. Does a great job and I am thinking of buying one for other rooms of the house.